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  <title>Enable/disable asynchronous signal handling or return the old setting</title>
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  <div id="layout-content"><div id="function.pcntl-async-signals" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">pcntl_async_signals</h1>
  <p class="verinfo">(PHP 7 &gt;= 7.1.0)</p><p class="refpurpose"><span class="refname">pcntl_async_signals</span> &mdash; <span class="dc-title">Enable/disable asynchronous signal handling or return the old setting</span></p>

 </div>

 <div class="refsect1 description" id="refsect1-function.pcntl-async-signals-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>pcntl_async_signals</strong></span>
    ([ <span class="methodparam"><span class="type">bool</span> <code class="parameter">$on</code><span class="initializer"> = <strong><code>NULL</code></strong></span></span>
  ] ) : <span class="type">bool</span></div>

  <p class="para rdfs-comment">
   If the <code class="parameter">on</code> parameter is omitted,
   <span class="function"><strong>pcntl_async_signals()</strong></span> returns whether asynchronous signal
   handling is enabled. Otherwise, asynchronous signal handling is enabled or
   disabled.
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.pcntl-async-signals-parameters">
  <h3 class="title">参数</h3>
  <dl>

   
    <dt>
<code class="parameter">on</code></dt>

    <dd>

     <p class="para">
      Whether asynchronous signal handling should be enabled.
     </p>
    </dd>

   
  </dl>

 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.pcntl-async-signals-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   When used as getter (that is without the optional parameter) it returns
   whether asynchronous signal handling is enabled. When used as setter (that is
   with the optional parameter given), it returns whether asynchronous signal
   handling was enabled <em class="emphasis">before</em> the function call.
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.pcntl-async-signals-seealso">
  <h3 class="title">参见</h3>
  <ul class="simplelist">
   <li class="member"><a href="control_structures.declare.html" class="link">declare</a></li>
  </ul>
 </div>


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